1. Field of the Invention
The present invention relates to a core drilling machine for drilling holes in concrete structures such as manhole risers, for example, to allow pipes to be attached to the concrete structures.
2. Description of the Related Art
Concrete structures are often used in municipal water and sewer systems and in other groundwater systems, for example, as manhole risers to which underground pipes are connected. Typically, the concrete structures are cast in the form of concrete boxes or concrete cylinders having a square or round wall, a floor, and an open upper end. After the concrete structure is cast, one or more circular holes are drilled in the wall or walls of the concrete structure to provide an interface to which an underground pipe may be attached via a sealing assembly. Typically, the sealing assembly includes an annular gasket, an expansion band mechanism for sealing the gasket within the hole in the wall of the concrete structure, and an external clamping band for sealing the annular gasket to the outer surface of the pipe.
One known machine assembly 10 for drilling holes in concrete structures is shown in FIG. 1, and includes a drilling machine 12 generally including frame 14, a drive unit 16, such as an electric or hydraulic motor, and a single drill bit 18 rotatably driven by the drive unit 16. The machine 12 is typically fixed to the floor of a building adjacent a turntable 20 upon which a concrete structure CS is supported. The machine 12 includes a drill bit translation device, such as a hydraulic cylinder 22, to move the drill bit 18 toward and away from the concrete structure to drill a hole in a wall of the concrete structure. The turntable 20 may be rotated to align different portions of the wall or walls of the concrete structure with the drill bit 18 in order for the machine 12 to drill multiple holes in the concrete structure. Also, the height of drill bit 18 is vertically adjustable with respect to frame 14 of the machine 12 to vary the vertical location at which holes are drilled in the concrete structure. After a desired number of holes are drilled in the concrete structure, the concrete structure is moved off of the turntable 20, such as by a crane, and another concrete structure is moved on to the turntable to drill holes therein.
Thus, the operation of the assembly 10 involves three separate movement axes, including a horizontal drilling axis and a vertical adjustment axis associated with machine 12, and a vertical rotational axis associated with turntable 20.
Although the assembly shown in FIG. 1 has proven to be effective, the need to adjust the rotational position of the turntable and/or the vertical height of the drill bit between each drilling operation, as well as the movement of the concrete structures onto and off of the turntable, can be time consuming and laborious.
Another machine assembly 24 for drilling holes in concrete structures is shown in FIG. 2, in which the machine 12 of FIG. 1 or a similar machine is disposed adjacent a pair of turntables 20a and 20b which are positioned side-by-side. The machine 12 is mounted on a set of tracks 26 adjacent the turntables 20a and 20b and is movable along the tracks 26 to traverse along a horizontal axis between positions in which the machine 12 is aligned with a respective turntable 20a or 20b. The operation of the drilling machine 12 is otherwise identical or similar to that described above.
Thus, the operation of assembly 24 involves five movement axes, including a horizontal traverse axis, a horizontal drilling axis, and a vertical adjustment axis associated with machine 12, as well as a pair of vertical rotational axes associated with turntables 20a and 20b, respectively.
Assembly 24 represents an improvement over assembly 10 described above in that the drilling machine 10 of assembly 24 may drill holes in a first concrete structure CS mounted to a first turntable 20a while a second concrete structure CS is moved onto or off of the second turntable 20b. Thereafter, the machine 12 traverses along tracks 26 and the horizontal traverse axis from the first turntable 20a to the second turntable 20b and then performs drilling operations with respect to the concrete structure CS on the second turntable 20b while the concrete structure CS on the first turntable 20a is removed and replaced with another concrete structure.
Although the assembly shown in FIG. 2 alleviates the need to entirely stop the operation of the machine while concrete structures are moved onto or off of a given turntable, the need to adjust the rotational position of a turntable and/or the vertical height of the drill bit between each drilling operation, as well as the traversing movement of machine 12 along tracks 26, may be time consuming and laborious. Also, the tracks 26 of the assembly 24 are mounted along, and cover, a relatively large area of the building floor on the side of the first and second turntables 20a and 20b on which machine is disposed. Further, the machine must be anchored securely in place prior to drilling to reduce vibrations and prevent the rotational torque of the drill bit from interfering with the lateral position of the drilling machine.
What is needed is a drilling machine assembly for concrete structures which is an improvement over the foregoing.